Understanding the deterioration of fresh brown rice noodles from the macro and micro perspectives

Prediction of the Ecological Behavior of Burkholderia gladiolus in Fresh Wet Rice Noodles at Different Temperatures and Its Correlation with Quality Changes

Burkholderia gladioli pathovar cocovenenans (BGC) is a highly lethal foodborne pathogen responsible for outbreaks of food poisoning with the highest recorded mortality rates among bacterial foodborne illnesses in China. In this study, the ecological behavior of BGC and its Bongkrekic Acid (BA) production dynamics in fresh wet rice noodles (FWRN) were investigated under isothermal conditions ranging from 4 °C to 37 °C. Growth kinetics were modeled using the Huang, Baranyi, and modified Gompertz primary models, with secondary models (Huang square root model and Ratkowsky square root model) describing the influence of temperature on growth parameters. Among these, the Huang-Huang model combination exhibited the best performance, with a root mean square error (RMSE) of 0.009 and bias factor (Bf) and accuracy factor (Af) values close to 1. Additionally, we examined the impact of BGC contamination on the quality attributes of FWRN, including pH, color (L*, a*, b*), hardness, and moisture content. The results indicated that BGC growth significantly increased pH and yellowing (b*) values, while changes in texture and moisture were less pronounced. A probabilistic model was further developed to predict BA production under various temperature scenarios, revealing that BA formation was most likely to occur between 24 °C and 30 °C. While this study provides valuable predictive tools for microbial risk assessment and quality control of FWRN, limitations include the exclusion of additional environmental factors such as oxygen and relative humidity, as well as the lack of direct investigation into the degradation behavior of BA. Future research will expand model parameters and include sensory evaluations and advanced microbiological analyses to enhance applicability under real-world storage and transportation conditions.

Effect of Canna edulis starch addition on the properties of flour, rheology of dough and quality of semi-dry noodles

BACKGROUND

Canna edulis is a high-quality resistant starch raw material, especially for making flour products. This study aimed to investigate the effect of Canna edulis starch (CES) on the properties of flour, rheology of dough and quality of semi-dry noodles. The CES replaced part of the wheat flour in the semi-dry noodle formula. One control formula containing wheat flour only, and five formulations based on wheat flour containing 8CES, 16CES, 24CES, 32CES and 40CES were prepared.

RESULTS

The findings revealed that with the increase of CES, the peak viscosity and retrogradation value of the flour increased, and the melting enthalpy decreased. CES caused some bound water to migrate to a semi-bound water state, improving the rheological properties of the dough and enhancing the texture characteristics of the noodles. When the added amount of CES was 24%, the cooking loss rate was 1.687%, and the highest sensory score was 86 points. Simulation of starch in vitro digestion revealed that the hydrolysis rate of starch first increased and then decreased with the increase of CES addition, with the highest proportion of resistant starch content ranging from 44.27% to 79.66%. Compared with the control group, the expected glycemic index decreased after adding CES.

CONCLUSION

These results assist in realization of comprehensive utilization of Canna edulis resources for the production of noodles with desirable qualities. © 2025 Society of Chemical Industry.

Enhancing the physicochemical qualities and consumer acceptability of rice noodles through yeast fermentation

Fermented rice noodles (FRN) are popular in many Asian countries due to their extraordinary flavor and mouthfeel. However, they havea short shelf life, inconsistent texture and sensory properties caused by uncontrolled microbial activity during fermentation. Furthermore, the lack of gluten contributes to their weak texture due to reduced cohesion and extensibility. The impact of yeast fermentation on the cooking, textural properties, microstructure, and consumer acceptability of cooked rice noodles (RN) was investigated. Yeast fermentation significantly enhanced the overall quality of cooked RN. FRN had a lower pH than conventional rice noodles (CRN), owing to the organic acids produced during fermentation. Notably, FRN subjected to a 3-hour fermentation period (FRN3) achieved the highest cooking yield, shortest optimum cooking time, and lowest cooking loss among all RN samples. This achievement is linked to the creation of multiple irregularly sized pores within the starch network, resulting from carbon dioxide generation and starch hydrolysis by microbial metabolites during yeast fermentation. Yeast fermentation decreased lightness and increased yellowness in RN, altering their color attributes. FRN3 earned the highest score for overall acceptability in sensory evaluations due to its superior appearance, taste, and texture. These findings open new avenues for future research on using yeast starter culture to enhance rice products and contribute to developing improved RN products with desirable sensory and textural properties.

(E)-2-Hexenal-loaded ethyl cellulose/agarose aerogel: Preparation, characterization and application in fresh rice noodles preservation

This study aimed to develop food-grade ethyl cellulose/agarose aerogels for the controlled release of plant essential oils to extend the shelf life of fresh rice noodles. The antibacterial efficacy of ten unsaturated aldehyde essential oils was evaluated against primary spoilage bacteria, including Leuconostoc lactis, Lactococcus lactis, Acinetobacter johnsonii, Exiguobacterium indicum, and Enterobacter sichuanensis. Based on its superior antimicrobial performance, (E)-2-hexenal was selected for encapsulation within ethyl cellulose/agarose aerogels to achieve controlled release and extend the shelf life of fresh rice noodles. Increasing the ethyl cellulose concentration resulted in a more uniform pore size distribution, enhanced mechanical properties and hydrophobicity, and improved controlled release of (E)-2-hexenal in the aerogels. The optimized aerogel, loaded with 0.20 μL/mL of (E)-2-hexenal, exhibited significant antimicrobial activity, effectively inhibiting bacterial growth for 72 h. Moreover, the aerogel formulation effectively preserved the quality of fresh rice noodles by mitigating changes in total plate count, pH, water content, water activity, cooking properties, color, and texture, ultimately extending the product's shelf life by 4 days at 25 °C. These findings highlight the potential of ethyl cellulose/agarose aerogels loaded with (E)-2-hexenal as an innovative preservation strategy for fresh rice noodles, providing a promising method for enhancing food quality and longevity.

Impact of flour particle size on digestibility and gut microbiota modulation in brown rice noodles: Balancing cell wall disruption and starch damage

Brown rice noodles are recognized for their health benefits. While previous research has focused on improving noodle properties through various processing conditions, the effects on digestibility and fermentability remain unclear. This study comprehensively investigated how brown rice flour particle size influences noodle digestibility and gut microbiota fermentation in vitro. Particle size first affects flour properties. The average particle size of BR15 flour (62 μm) falls between the length and width of the endosperm cells, effectively disrupting the cell walls while minimizing excessive starch damage, thus achieving an optimal balance and resulting in the highest peak viscosity. As a result, brown rice noodles made from BR15 flour exhibited the lowest starch digestibility in vitro. X-ray diffraction analysis revealed that starch crystals in digestive residues were predominantly V-type, with BR15 showing the highest relative crystallinity. In vitro fecal fermentation indicated elevated Bifidobacterium abundance and butyrate production for BR15 noodles compared to others. The moderate particle size of BR15 brown rice flour imparts unique digestibility and gut microbiota modulation to the noodles produced. This study provides insights into particle size optimization for improving nutritional quality of brown rice noodles.

Effect of surfactin on microbial content, appearance quality, and starch properties of fresh noodles during storage

Fresh noodles (FNs) are prone to quality deterioration during storage, negatively affecting their edibility. This study investigated the impacts of different surfactin concentrations on microbial content, appearance quality, and starch properties in FNs to enhance storage stability and shelf life. The addition of surfactin effectively controlled the microbial growth in FNs during storage, FNs containing 0.4 % surfactin maintained total aerobic plate count below 106 CFU/g for up to 72 h at 25 °C, which was at least 48 h longer than the control group. Furthermore, surfactin could inhibit yellowing and reduce the appearance of dark spots in FNs during storage. Results from Rapid Visco Analyzer, X-ray diffractometer, and Differential Scanning Calorimetry indicated that surfactin inhibited the decrease in starch viscosity, and the increase in relative crystallinity and enthalpy, and improved the storage stability of starch in FNs. This research provides a theoretical foundation for applying surfactin as an enhancer in FNs.

Insights into the effect mechanism of freeze-thaw cycles on starch gel structure and quality characteristics of frozen extruded whole buckwheat noodles

The effects of freeze-thaw cycles (FTC) on starch gel structure and quality characteristics of frozen extruded whole buckwheat noodles (FEWBN) were studied. The repeated FTC treatments induced the retrogradation of amylose which increased the compactness, crystallinity, hardness, and cooking time of FEWBN. However, with the increasing number of freeze-thaw cycles, the larger volume of ice crystals formed in the noodles destroyed the starch gel network structure to a certain extent, and led to the dehydration and syneresis of the noodles, and the quality deterioration. However, moderate amylose retrogradation occurred during the FTC treatment was found to be beneficial for the quality of FEWBN. After one time of FTC treatment, the cooking loss of 3.53 % was even lower compared with that without FTC treatment (4.61 %). After seven times of FTC treatment, the cooking loss of FEWBN was 6.53 %, and the breaking rate was still 0, indicating that FEWBN could resist the damage caused by temperature fluctuations on the internal structure of frozen food to a certain extent, and maintain good quality. This study establishes a fundamental basis for the development of buckwheat noodles with good freeze-thaw stability and high cooking quality.

Survival, Growth, and Toxin Production of Bacillus cereus During Cooking and Storage of Fresh Rice Noodles

Retail stores maintain fresh rice noodles (FRNs) at room temperature because refrigeration negatively impacts FRNs' texture. The room temperature and high water activity of FRNs help spore-forming Bacillus cereus to grow and produce toxins. In this study, the effect of steam cooking on survival and different storage temperatures on the growth and enterotoxins production of B. cereus in FRNs were investigated. White rice flour was used to make FRNs. Three treatments of FRNs were used in this study; uninoculated, inoculated (with 4.0 log CFU/ml of B. cereus spores), and autoclaved as a negative control. A slurry of rice flour, cornstarch, and water was steam cooked for 4 min at 90°C and incubated for 168 h at 4°C, and for 72 h at 22 and 32°C. Incubated FRNs were tested for pH, B. cereus growth, and enterotoxins production. Steam cooking reduced the total number of B. cereus spores by 0.7 ± 0.3 log CFU/g. Surviving B. cereus spores in inoculated and uninoculated FRNs germinated over 72 h of storage. No B. cereus was detected in negative controls. An interaction was observed across storage temperatures and time (p < 0.05). The B. cereus population in uninoculated FRNs increased by more than 7.0 log CFU/g at 22 and 32°C over 72 h, while inoculated FRNs showed a 5.0 log bacterial increase at these storage temperatures. No growth was observed at 4°C in both inoculated and uninoculated FRNs. The pH of inoculated FRNs was reduced from 6.9 ± 0.1 to 5.7 ± 0.0 at 32°C and to 6.2 ± 0.1 at 22°C, and the pH of uninoculated FRNs was reduced from 7.0 ± 0.1 to 5.8 ± 0.2 at 32°C and to 6.5 ± 0.0 at 22°C, indicative of FRNs spoilage. B. cereus in inoculated FRNs produced enterotoxins after 12 h of storage at 32°C, and over 24 h of storage at 22°C, while no toxin was detected at 4°C. Our findings show that storing FRNs at room temperature for 24 h leads to enterotoxin production, emphasizing the importance of proper FRN storage and their potential risk to consumers. Nevertheless, further research should investigate the effect of other foodborne pathogens on these products.

Properties of pyrodextrinization corn starch and their inhibitory effect on the retrogradation of fresh rice noodles

This study was aimed to investigate the properties of pyrodextrins under different preparation conditions and the effects of pyrodextrins on the retrogradation of fresh rice noodles. Pyrodextrins were made by heating corn starch with and without lactic acid at 180 °C ranging from 1 to 6 h. The molecular weights of pyrodextrins gradually decreased, whereas the branching degree increased and the chain length shrank with the prolongation of heating time. The changes of acid-heat-treated pyrodextrins were more pronounced than those of dry-heat-treated pyrodextrins under the same treatment time. The acid-heat-treated pyrodextrins displayed higher water solubility and lower viscosity, suggesting that they could no longer gel. These results suggest that starch retrogradation could be limited by pyrodextrins, especially acid-heat-treated pyrodextrins. Then, the pyrodextrins were added to fresh rice noodles and the eating and cooking qualities were examined during storage. After 35 days of storage, the pyrodextrin with acid heating at 180 °C for 4 h showed the most effective inhibition on starch retrogradation and was suitable for fresh rice noodles as an anti-retrogradation agent. The study might supply new perspectives on restraining starch retrogradation and promoting the fresh rice noodle industry.

Ordered structural changes of retrograded instant rice noodles during the long-term storage

Temperature-induced textural, cooking properties and structural variations of retrograded instant rice noodles (IRN) during the long-term storage were systematically investigated. IRN samples stored at 4 °C exhibited a relative high cooking loss (2.45 %), and their hardness values gradually increased with prolonged storage. Moreover, the higher storage temperature (35 °C) accelerated the deterioration of IRN texture. Fresh IRN displayed a typical B-type XRD pattern with 9.65 % relative crystallinity (RC). During the initial 2 weeks of storage, the formation of a long-range ordered structure led to an increase in RC, which was closely related to the duration and temperature of storage (ranging from 4 °C to 25 °C to 35 °C). Over the 12-week storage period, there was likely a disorganization of the supra-molecular structure, as evidenced by the considerably decreased RC and reduced water mobility. Furthermore, Pearson's correlation analysis highlighted that the tight integration between starch molecules and water molecules endowed IRN samples with enhanced smoothness and tenderness in flavor profiles. Hence, the study is expected to provide a comprehensive understanding of the mechanisms underlying molecular order changes in retrograded starch gel products during the long-term storage.

Effect of Bacteria Content in Wheat Flour on Storage Stability of Fresh Wet Noodles

The effect of bacteria content in wheat flour on shelf life and storage stability of fresh wet noodles (FWNs) was evaluated in this study. Nine kinds of wheat flour with different bacterial contents were selected to make FWNs. With the increase in total plate count (TPC) from 120 CFU/g to 5500 CFU/g in flour, the shelf life of FWNs decreased from 23 d to 9 d at 4 °C. During storage, the acidity increased, which was significantly correlated with the change of TPC (p < 0.05), and the pH value and L* value of FWNs decreased significantly (p < 0.05). Changes in viscosity characteristics of starch components were also detected, the higher the TPC in flour, the more obvious the viscosity decreased. Moreover, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that with the deterioration of FWNs, some low molecular weight protein subunits increased; texture analysis showed that the hardness of noodles increased firstly and then decreased, the adhesiveness increased and the springiness decreased during storage. In summary, choosing flour with low TPC to prepare FWNs can extend the shelf life and slow down the quality deterioration of FWNs during storage at 4 °C.

Understanding the Changes in Quality of Semi-Dried Rice Noodles during Storage at Room Temperature

The changes in semi-dried rice noodles during storage at room temperature (25 ± 2 °C) in terms of microbial growth, cooking quality, color, textural properties, thermal properties, crystallinity, and moisture content, and moisture distribution was examined. Total plate count, cooked broken rate, cooking loss, and b* value increased, while rehydration ratio, L* value, and moisture content decreased during storage. The hardness, adhesiveness, and chewiness of semi-dried rice noodles increased significantly, according to textural properties. DSC and XRD showed that the enthalpy of thermal absorption and crystallinity of semi-dried rice noodles increased from 1.67 J/g and 3.48% to 4.21 J/g and 18.62%, respectively. LF-NMR showed that the weakly bound water content in semi-dried rice noodles decreased by 3.71%, and the bound water content and free water content increased by 3.20% and 0.51%, respectively. The results of correlation analysis showed that the changes in quality during storage of semi-dried rice noodles were influenced by the combination of microbial growth, aging of rice noodles, and moisture migration.